A number of attempts have been made to treat selected materials so as to render them oleophilic and hydrophobic. These methods include coating a material with silicone, with vegetable oils, etc. Charcoal has also been proposed as an absorbent but charcoal is hydrophilic and sinks in water.
In general the sorbent materials provided by the prior art are all relatively expensive. Some of the recent U.S. Pat. describing different types of sorbent materials are Fanta et al. No. 4,605,640, Mandel No. 4,770,715, Sandberg No. 4,787,773 and Raible No. 4,925,343.
In addition, Grenthe No. 4,753,917 discloses the subjecting of fibers of cellulosic material to rapid forced heating to expand the fibers to form a sorbent material.
Pyle No. 3,950,143 discloses the forming of a fuel from woody material by pyrolysis type toasting of woody material at temperatures above 380.degree. C.
Yvan No. 4,553,978 discloses forming a torrefied biomass by heating biomass to a temperature between 200.degree. C. and 280.degree.C.
A publication entitled SORBENTS FOR OIL SPILL REMOVAL by Paul Schatzberg discusses the properties of various materials that have been used as sorbents.